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The BOLEO CopperThe BOLEO Copper

ProjectProject

September 2002September 2002



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BOLEO Copper Deposit

• Located in Baja California, Mexico

• Ore is complex, fine grained oxide,sulphide and mixed oxide / sulphidecontaining 40% clay

• Treatment is complex



3

Project History1997

• Project optioned by International CuratorResources

• Fluor Daniel Wright conducted feasibility

study based on extensive testwork byLakefield, CMRI, Pocock and others

• Complex process with high capital andoperating costs

• Project put on hold



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Ore Preparation

- SAG Mill

Oxidation

Leach

Reduction

Leach

Neutralization

In-Pulp Sulfide

Precipitation

Bulk Sulfide

Flotation

Filtration and

Washing

Concentrate

Roasting

Calcine

Leaching

Copper SX/EW

Zinc SX/EW

Cobalt SX/EW

Boleo Ore Rejects

H2SO4

H2SO4 + SO2 + S

High Acid

Consuming Ore

H2S

Floatation ReagentsFloatation Tails

to Disposal

Wash Water

Filtrate to Leach

Air SO2 to Leach

H2SO4 + Water

Copper Cathode

NaOH

NaOH

Zinc Cathode

Cobalt Cathode

Waste Solution to Disposal

Fluor 97 Base Case



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Project History2001 - 2002

• Project returned by Mintec InternationalCorporation

• Bateman asked to review 1997 study and

develop a simpler, conventional, process• Conducted scoping study for simpler, lessexpensive process, based on previous test

reports• Proposal for full feasibility study with

additional testwork



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Geology and Mineralogy

• Boleo’s Cu-Co-Zn mineralisation occursin mantos with gradation in mineraltype and metal grade from a distinct

(barren conglomerate) footwall overlaindirectly by high grade ore to a less

distinct gradational hanging wall.



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Mineralogy (Continued)• 1955 US Geological Survey study of the

Boleo deposit provides an overview of thecomplex and highly variable mineralogy of

the manto structures. Notable featuresinclude;



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Mineralogy (Continued)

High clay content (up to 60%);Saline in-situ water content of 20-25%;

Large variety of oxide mineralization,including simple oxides, carbonates,oxychlorides, silicates and mixed

(ferrite) oxides;Sulfides, when present, of extremely finegrain size.



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Process Implications

• Solid – Liquid Separations will beChallenging due to Clayey Oretypes

• Process in Seawater (high chloride) dueto Salinity of Natural Ore

• Must Use a Variety of Chemistries to

Dissolve all Metal (Cu/Co/Zn) Minerals



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Design Objectives

• Keep it Simple• Inexpensive

• Use proven process steps• Maximum use of previous testwork data



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Design Basis

11,500 t/d

47,000 t/aCopper production

2,750 t/aCobalt production

20,000 t/aZinc production

5.54 %MnO2

0.62 %Zn (oxide and sulfide)0.089 %Co (oxide and sulfide)

1.36 %Cu (oxide and sulfide)

Average ore grade

4,025,000 t/a Annual ore throughput



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Testwork Review

• Extensive testing done on all unitoperations for previous study

• Some results appeared to have been

overlooked (thickening) and have beenrevisited

• Conclusion – Testwork data would form good basis fordevelopment of new process



13

Process Options Review

• Seven process options considered andassessed according to

– Technical viability (proven vs. novel)

– Perceived capital and operating costs

– Operability

• One option chosen as base case forscoping study



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Major Process Changes

• Removal of sulphide flotation androasting operations

• Addition of CCD circuit for solid-liquidseparation to allow base metal recoveryfrom SOLUTION, NOT SLURRY

• Based on high rate thickening testresults from previous work



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Thickening Testwork Review• Tests done by Pocock Industrial Inc on leach residues

• Initial tests indicated settling rates of up to 2 m2 /t/day.These high figures preclude efficient use of CCD circuit –hence flotation-roasting option considered previously.

• Two high-rate thickening tests at end of test campaignshowed settling rates of 0.1 m2 /t/day. These resultsappear to have been overlooked in previous study.

• Results reviewed by Bateman and Delkor

• Decision taken to proceed on basis that high-ratethickening test results are indicative of full-scaleoperation.

• Follows Bateman experience on similar clayey ores (eg.Bulong)



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Process - Basic

MILLOXIDISING

LEACH

REDUCING

LEACHCCD

Cu

SX / EW

SULPHIDE

PRECIP

SULPHIDE

LEACH

Zn

SX / EW

Co

SX / EW

Acid SO2 Water

Tailings

Copper

CobaltZinc

Oxygen

H2S

Tailings

Leach

Residue



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Process - Detail

OX

LEACH

RED

LEACH

NEUT 1

CCD

NEUT 2

TAILINGS

Cu SX

Cu EW

NEUT 3SULPHIDE

PRECIP

SULPHIDE

LEACH

Fe

REMOVAL

Cu / Cd

CEMENT

Zn SX 1Zn EW Zn SX 2

NEUT

Co SXCu / Zn

IX

Co EW

Ore

Acid

SO2

HAC

Zinc

Cathode

HACLime

Air

Decant Tailings

Copper

Cathode

HAC H2S O2

Air

Limestone

Zn Dust

Cobalt

Cathode

NaOH

NaOH

Limestone

Air

Water



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ProcessCrushing & Milling

• Primary jaw crusher

• Scrubber for clay removal

• Single stage ball mill for scrubber

oversize

• Cyclone classification

• 40% w/w solids @ P80 = 200 µm



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ProcessLeaching

• Two stage leach maximises recoveries

• Oxidising leach – Majority of copper and some zinc leached

– High acid consumption due to gangue• Reducing leach

– Metal values associated with manganesedioxide (mainly cobalt) leached

– Reducing conditions maintained with SO2



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Leach Chemistry

• Oxidizing Leach Using Natural MnO2 in ore

MS + MnO2 + 2H2SO4 = MSO4 + MnSO4 + 2H2O + S

where M = Cu, Co, Zn

• Reducing Leach Using Sulfur Dioxide Addition

MnO2 + SO2 = MnSO4

cobalt in Mn-Oxide is leached



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Ore Characterization Tests(From Fluor Study)

Bed

Number

No. of

Intervals

Sulfide

(%)Carbonate

(%)

Net MnO2

(%)

2 27 0.09 7.06 9.8

3AA 9 0.28 2.15 8.1

3A 78 0.82 4.49 7.9

3 147 0.24 3.40 5.9



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ProcessLeaching

• Overall Leach recoveries

– Copper 91%

– Cobalt 87%

– Zinc 73% – Manganese 97%

• Acid consumption ~180 kg/t ore• SO2 consumption ~ 25 kg/t ore



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ProcessStage 1 Neutralisation

• Partial neutralisation with high acidconsuming ore (HAC)

• Product solution is amenable to Cu

SX/EW• Two functions:

– Raise pH after leaching – Oxidise Cu1+ to Cu2+ (air sparging)



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Neutralization Chemistry

• High Acid Consuming Ore is Available atSite and Contains Ca/Mg Carbonates

H2SO4 + CaCO3 → CaSO4 + H2O + CO2

H2

SO4

+ MgCO3

→ MgSO4

+ H2

O + CO2



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ProcessCCD

• Six large thickeners

• Washing with discharge solution fromsulphide precipitation (free of copper,

cobalt and zinc), plus sea water make-up

• 97% washing efficiency



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ProcessStage 2 Neutralisation

• Tailings neutralisation with HAC andlime

• Neutralisation to pH 5 to 6 for soluble

metal precipitation• Manganese not precipitated – contained

in soluble form in tailings dam



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ProcessCopper SX from Partially Neutralized Leach Solution

• Extraction with LIX984N @ 15% v/v

• Extraction – 2 mixer settlers

– 98% extraction

• Scrubbing – 1 mixer settler

– Removal of entrained manganese and chloride

• Stripping – 2 mixer settlers

– Stripping with EW spent electrolyte



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ProcessCopper EW

• Electrowinning under standardconditions

• LME Grade A copper produced



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ProcessStage 3 Neutralization

• Neutralization with HAC

• Two functions:

– Neutralize acid generated in copper SX

– Precipitate residual iron prior to sulphideprecipitation



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ProcessSulphide Precipitation

• Acts as primary purification step for zincand cobalt

• Zinc, cobalt and residual copper

precipitated with H2S gas• Iron, manganese, magnesium,

aluminium and calcium remain insolution (recycled to CCD in wash)



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ProcessSulphide Leach

• Precipitated sulphides dissolved at high

efficiency in oxidising pressure leach @150°C

• Sulphur oxidation controlled to producesome elemental sulphur (assists withoverall sulphur balance)

• Acid provided in recycle from primaryzinc SX



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ProcessSolution Purification

• Zinc / cobalt solution purified in two stages

• Stage 1

– Iron removal by precipitation using limestone andair

– Some copper removed

• Stage 2

– Cadmium removal with zinc dust – Residual copper removed



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ProcessZinc SX

• Extraction with D2EHPA @ 40% v/v

• 2 stage extraction with intermediateneutralisation

• Primary extraction – 1 Bateman Pulsed Column

– No pH control

– 60% extraction

– Raffinate split• 75% to sulphide leach

• 25% to neutralisation



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ProcessZinc SX

• Intermediate neutralisation

– pH raised using limestone – Residue recycled to oxidising leach

• Secondary extraction – 1 Bateman Pulsed Column

– pH control using sodium hydroxide

– 99.5% extraction

– Loaded organic to primary extraction



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ProcessZinc SX

• Scrubbing

– 3 mixer settlers – Physical removal of entrained impurities as well as

chemical scrubbing of calcium

• Stripping – 1 Bateman Pulsed Column

– Stripping with EW spent elecrolyte

• Regeneration – 1 mixer settler

– Iron removal from bleed using 6M HCl



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ProcessZinc EW

• Electrowinning under standardconditions

• SHG zinc produced



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ProcessCobalt SX

• Extraction with Cyanex 272® @ 25% v/v

• Extraction – 1 Bateman Pulsed Column

– pH control using sodium hydroxide

– 99.95% extraction

• Scrubbing – 2 mixer settlers

– Primarily for nickel removal

• Stripping

– 1 Bateman Pulsed Column – Strip solution dependant on cobalt product



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ProcessCobalt Purification - IX

• Residual copper, zinc and others

removed from cobalt electrolyte by ionexchange

• IX columns in “lead-lag” configurationfor maximum efficiency



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ProcessCobalt EW

• Electrowinning under standard

conditions in undivided cells

• Alternative for cobalt sulphideproduction also considered



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ProcessReagents

• Elemental sulphur imported for production of

– H2SO4 (produced in acid plant)

– SO2 (produced in acid plant sulphur burner)

– H2

S (produced from molten sulpur andhydrogen from Naphta reformer)

– Acid plant generates 31 MW net power

• Limestone milled on site• All other reagents used as supplied



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Major Reagent Consumptions

386,000

1,948,000

2,038,000

882,000

1,224,000

7,000,000

Cost

US$

Consumption

t/a

SX Organic Reagents

7,800Sodium Hydroxide

760Flocculant

14,000Hydrogen Sulphide

87,400Sulphur Dioxide*

764,400Sulphuric Acid*



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Metsim ModellingGeneral

• Metsim model set up to calculate

– Flows and compositions of major streams,including recycles

– Major reagent consumptions

– Heating and cooling requirements• Steady-state simulation using simple unit

operations used to simulate more complex

real-life operations• Testwork data and information from previous

studies used where possible



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Metsim ModellingMass Balance Calculations

• High level of accuracy

• 73 components considered in 4 phases – 42 inorganic solid

– 16 inorganic aqueous

– 8 organic aqueous – 7 gaseous

• Major elements include Cu, Co, Zn, Ni, Fe,Mn, Mg, Na, S, Ca, Si, Cl



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Metsim ModellingEnergy Balance Calculations

• Lower level of accuracy

• All stream temperature calculations done byMetsim using thermo data from Metsimdatabase and other sources

• Heat loss from equipment not simulated

• Heat exchangers simulated using steam or

cooling water – no solution interchangesimulated due to model stability



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Metsim ModellingFeed Mineralogy

• Not readily available from previous work

• Mineralogy developed based on

– Previous test results

– Recent sample analyses• Oxide / sulphide split difficult to determine

with any accuracy

• Mineralogy adjusted to produce acid and SO2

consumptions consistent with test results



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Metsim ModellingFeed Mineralogy

SiO2MgSO4

MgCO3CaCO3

MnO2

FeOOH

0.02NiO

Balance0.56ZnO0.350.33ZnS

5.770.08CoO4.000.026CoS

5.541.28CuO

9.230.41Cu2S

%%



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Metsim ModellingResults

• Model results compare well with available test

data and general plant operating data• Excellent tracking of impurities and water

balance issues

• Energy balance results suitable for sizing of heat exchangers

• Metsim model an invaluable tool for accurateplant design

• Model can be easily and quickly adapted formore detailed design during feasibility study



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Capital CostsDirect Field Costs (US$)

202,439,000TOTAL DIRECT FIELD COSTS

7,269,000Transport

8,296,000Infrastructure

5,862,000Instrumentation

14,639,000Electrical

17,885,000Pipework

13,430,000Structures

18,748,000Concrete

6,134,000Site Development / Earthworks

53,681,000Mechanical Equipment

56,495,000 Vendor Supply and Install Packages



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Operating Costs

28,964,551

7,086,347

17,715,687

2,558,652

4,559,194

US$/a

7.96TOTAL OPERATING COST

1.76Power

4.40Consumables

0.64Maintenance

1.14Labour

US$/t



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Summary and Conclusions

• Boleo ores can be settled in High RateThickeners

• Conventional CCD will work

• Cu, Co and Zn recovered from solutionas high quality, saleable products



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Example Projects - Bateman

Mt Gordon



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Insert picture of Mt Gordon Expansion Project

Mt Gordon

Gunpowder Autoclave



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Gunpowder Autoclave

Bulong Nickel Plant



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Ore Preparation

Pressure LeachCCD

SX

Electrowinning

Bulong Nickel Plant

Kasese Cobalt



61

Kasese Cobalt

Olympic Dam Expansion



Olympic Dam Expansion

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